The production generally of food product chips by the formation of a ground dough or masa that is formed into ribbons and chips and deep-fried in oil is well known in the art.
The preparation of dough, where corn is employed, for example, and corn chips constitute the desired product, is accomplished generally by steeping of the corn in water to which calcium hydroxide has been added. The mixture is normally cooked, partially or substantially completely, with at least partial gelatinization, and the resulting mixture is then drained to remove the lime water and associated components occurring in the mixture whereupon the residual corn product is washed with additional water and ground to provide a moist dough or corn paste known as "masa". The masa is formed by a variety of known processes into ribbons or sheets by extrusion or sheeting, a step in which the masa is compressed, and subsequently formed into pieces that are fried to yield the desired chips.
The foregoing process, as generally described, has been varied, heretofore, to serve a number of different objectives with varying degrees of success.
In one embodiment, for example, the masa is formed into a thin sheet that is coated with a deposit of wheat flour to seal the masa, causing, it is asserted, a puffing or enlargement of the treated shell upon cutting thereof and cooking.
In a further embodiment, raw corn is cooked at 212.degree. F. (100.degree. C.) and at a neutral pH, to yield ultimately a sticky masa with undecomposed hulls that is mashed, in addition to being ground, to eliminate lumping within the masa and then passed through an extruder at high pressures but without regard to control of the elevated temperature induced by these high, but unspecified, pressures.
It has also been proposed that, in the formation of masa, the whole kernels of corn be cooked in a supersaturated solution of calcium hydroxide at elevated temperatures and pressures to, inter alia, abbreviate the period of time consumed in the initial process step and to more uniformly loosen the cellulosic shells or hulls from the kernels incorporated in the dough.
It has been known heretofore to produce a farinaceous ribbon of dough for frying and cutting into chips that includes extrusion of the dough at a pressure of 1500 to 2500 psi, but without any effort to control the temperature at which extrusion occurs. The objective in this instance has been, however, to secure a dough ribbon for frying of substantially uniform quality at a substantially constant rate that permits treatment of the dough ribbon recovered from the extruder in extended, uninterrupted lengths.
Means for effectively reducing the fat or oil content of food chips and particularly corn chips and potato chips has also been long sought so that the product chips would have properties of crispness and lightness while avoiding the oil heavy flavor and sogginess so readily communicated to these chips in the manufacturing process.
In one embodiment proposed to achieve the foregoing objectives, heating of the corn is undertaken, in the absence of lime, at a temperature ascending to about 170.degree. F. (72.degree. C.) to avoid the formation of a dough "too sticky to roll and cut". The dough formed in the process is ground and hydrated simultaneously, and sequentially heated at apparently reduced pressures, and thereafter substantially dehydrated at an elevated temperature, prior to cutting and frying to form product chips. The object of this latter embodiment is a reduced oil or fat content in the chips secured, but this objective is achieved by presenting to the heated oil of the frying step substantially dry pieces of dough or half product in which there is a minimal amount of water and a substantially fluid impervious membrane, and therefore a minimal opportunity for replacement of the residual water, as well as air, present, by oil.
In a further embodiment, potato chips, specifically, are prepared by passing an admixture of potato flour with water, through an extruder at an elevated temperature and a pressure of at least 6 atmospheres (i.e. 90 psi). The extruded half-product is dried prior to frying into finished chips.
A still further variation, employed heretofore in the production of corn chips of lower fat content, suggests the addition of oil or fat shielding agents, such as carboxymethyl cellulose to a masa after extrusion thereof and drying of the product recovered to a moisture content of around 10 percent before deep frying. The half-product of this embodiment attains a hard, dry, horny exterior before frying. The product chips are normally highly puffed.
It has also been proposed that corn dough prepared from dried raw corn steeped in an aqueous lime solution under pressure, be comminuted by a process of cutting, kneading and mixing that replaces conventional grinding. The comminuted product assumes a size that combines, it is theorized, with the release of zein, oils and the like from the corn, permitting a plasticization without undue stickiness, which would otherwise interrupt the continuous process the proposed embodiment is intended to provide. No suggestion is made in the description of this process of any means to reduce the fat or oil content of the product corn chips.
In the event, therefore, that fried food product chips, and particularly, corn chips, characterized by a light frangible quality could be secured having a reduced concentration of air spaces and the like with organoleptic properties including taste and texture and with a significantly reduced fat or oil content, a material step forward in the state of the art would be attained.
Were it possible, additionally, to produce these chips by a method that is efficient, continuous, and avoids the interruption due frequently to a sticky masa passing through the extruder or sheeting device of the process, and the use of a dried half-product, a further substantial advance in the art will have been effected.